Impresser mechanism



June 13, 1944. A. M. MARKS 2,351,058 v IMPREssER MECHANISM Y Filed Nov.9, 1940 v s sheetssnet 1 INVENTO am on. am

IMPRESSER MECHANISM Filed Nov. 9, 194Q 3 Sheets-Sheet 2 [8g Y I" IINVENTOR wir Eycmmmm WM WLM ATTORNEY June'13, 1944. A. M. MARKS1351;058:

IMPRESSER MECHANISMl Filed Nov. 9, i940 Sheets-sheet 3 ATTogNEY PatentedJune 13,v 1944 f .2,351,05sv

Application November 9, 1940, Serial No. 364,985.

7 Claims.

My invention relates to a novel impresser mechanism and morespecifically my invention relates to a multiple impressing apparatusadapted to eiect transfer of a crystalline layer from crystalline masterblanks to receptive media.

In my copending application Serial No. 313,392, led January 11, 1940, Ihave disclosed a novel method for forming crystalline layerssuch aspolarizing iodocinchonidine sulphate crystals by transferring acrystalline field in the form of a layer from a crystalline master'blankwhich may be formed in accordance with'my Patents Nos.

2,104,949 and 2,199,227, to a receptive plastic medium by impressing thecrystal face of said master blank against said receptive plastic medium.

This transfer is preferably eiected under conditions of high vacuum,high pressure and raised Y temperature.

I have now devised a novel apparatus for simultaneously effecting themultiple transfer of such crystalline layers from a plurality of masterblanks to a receptive plastic medium, my apparatus being specicallydevised to provide the proper conditions of low surrounding atmosphericpressure, the desirable temperature conditions and the necessarypressures to effect the transfer. My apparatusis so devised that thecycle of operations which will be hereinafter more specically describedis effected automatically, the machine returning to its originalposition at the end of the cycle.

It is the object of my invention to provide a novel impresser apparatus.

It is av further object of my invention to provide a novel impresserapparatus forl effecting the transfer of crystallineelds.

It is a further object of my invention to provide a novel apparatus foreffecting the transfer of a crystalline field in the form of a layerfrom a master blank to a receptive plastic medium in the presence of asubstantial vacuum at elevated temperature and under relatively highpressure.

It is a further object of my invention to provide a novel apparatus foreffecting the transfer o'f a crystalline eld to a receptive medium inwhich apparatus a multiplicity of operations are carried out undervarious conditions, all of which are controlled by timers, relaycontrols and microswitches.

Further objects of my invention will be apparent from a consideration ofthe drawings, a specic description of which here follows:

' means 25 and 26. 'I'he lower edge 28 of the side- Figure 1 is a frontview and partial cross section'of the apparatus 'of my invention.

Figure 2 is a plan view taken along the line 2-2 of Figure 1.

Figure 3 is an enlarged cross section of the master blank holder whichis an element of my invention.

Figure 4 is a diagrammatic representation of the electrical controls andcircuits showing their' relation to various elements of my apparatuswhereby the cycle of operations of my machine is automatically eiected.y l

Figures 5, 6, and 'l are circuits which have been separated out fromFigure 4 in order to make clear the separate functions andinterrelations of the separate sections of` the circuit.

Figure 5 is the motor control circuit. Figure 6 is the timer controlcircuit. Figure 7 is the holding circuit.

Referring now more specifically to the drawings, in Figure 1 I show myimpresser apparatus mounted on a suitable standard I0. Fixed to thisstandard Il) is a heavy tension block I I in which are positionedtension rods I2 and I 3, the tension rods I2 and I3 being secured to thetension block II by suitable securing and locking means I 4 and I5.Mounted on the tension rods I2 and I3 isa cross bar Il which isresiliently forcedv upward by the coil springs I 8 and I9 which fitaround the tension rods VI2 and I3. Fixed to the center of the arm Il isa piston rod 20 which extends downwardly and at its lower terminuscarries a pressure transmitting head 2|. Yieldably carried on the pistonrod 20 and the pressure transmitting head 2| is a vacuum hood 22.

Positioned in the side wall 23 of the vacuum hood 22 is a window' 24fastened by suitable fastening wall 23 is adapted to be lowered into airtight engagement with the resilient gasket 29 seated in' the platengenerally denoted as 30.

The vacuum hood 22 rides freely on the piston rod 20 through 'the sleeve32 which is sealed to preserve the vacuum in the hood 22 by the sleevepacking 33 and the screw cap packing gland 34 which exerts the properpressure on the packing 33. A spring 36 exerts downward pressure onsleeve 32 at the lower seat thereof 31. The lower rally denoted as 30 isprovided with a centraily located suction line I0 which communicates atone end with the operating cham-y ber H and at the other end with a.suitable source of vacuum such as a vacuum pump, not here shown.

In order to provide heat or cold according to the requirements of theoperation the platen 30 has hollow passages 44 and 45 contained thereinwhich passages communicate with a suitable source of steam or hot orcold fluid through pipe fittings 45 and 41. 'I'he heat transfer effectedby such heating fluids raises or lowers the temperature of the platen 30and thus also of the receptive plastic ber 4|.

Although I have here disclosedas a heating means, passages for thereception and transmis--l sion of iluids, it is within the purview of myinvention to provide electrical resistance heating means or othersuitable means for heating or cooling.

As previously pointed out the outer edge of the platen 30 is providedwith a gasket 29 so that upon lowering of the vacuum hood 22a sealedoperating chamber 4| is obtained.

Seated in the platen 39 are removable backing surface plates 50 and 5|over which is adapted to be disposed a receptive plastic medium '52. Thevacuum ,outletv 53 of the vacuum pipe 49 also functions as a positioningmeans. The plastic sheet 52 has a punched lout central opening so thatthe sheet fits over the vacuum outlet.

This receptive plastic medium may be in the form of cellulose acetatesheeting coated with a suitable resin orfresinous mix that isthermoadhesive and therefore receptive to the crystalline layer which isto be transferred thereto.

Mounted and suitably xed in the platen 30 are rods 55 and 56'on whichare supported a riding carrier plate 51 by'means of springs 59 and 59.Springs 58 and 59 yieldably support the carrier plate 51 a shortdistanceabove the' backm'e'dium and the operating cham-1 30. Upon actuation ofthe starting mechanism, downward pressure is supplied to the piston rod25 which moves downwardly carrying the vacuum hood 22 towards thegasket29 set in the platen 90. There are two sensitive snap switches, one ofwhich |20 is operated when the gasket is compressed by the vacuum hood22 and the second of which 92 is actuated when the crossbar |1 has moveddown far enough to press the master blanks into the plastic sheet 52.Referring to Figure 4, the vacuum pump |82 is set in action and thesolenoid air vent |9| is closed, when the switch |20 is actuated by theextension arm 42 on the hood 22,' thereby' withdrawing air .from theoperating chamber 4| through the vacuum line 40. The downward movementof the piston rod 20 is stopped until a suitable vacuum has been reachedwithin the operating chamber 4|, which may be on the order of one mm, ofmercury. The vacuum hood 22 is resiliently maintained against the gasket29 by the pressure exerted by the spring 96 against the vacuum hoodat'91, the spring 95 being downwardly impelled by the crossbar l1, andalso by the differencebetween atmospheric pressure and the lowered airpressure within the hood. As soon as the proper degree of vacuum hasbeen elected within the operating chamber 4| the piston rod 20 again isimpelled downwardly through the air tight seal 99 in the sleeve 92whereupon the pressure head 2| moves downwardly and engages4 the mastering members 59 and 5| thereby making it possibie to apply a vacuumbetween the crystalline layers 64 and 65 of the master blanks 62 and 63and upper surface of the receptive medium 52 before pressing these partstogether. Loosely mounted in the carrier plate-51 are master blankholders 69 ,and 5I which carry aillxed thereto the above-mentionedmaster blanks 62 and 53, on the lower face oi' which is depositedcrystalline layers 64 and 65.

By referring now more specifically to Figure 3, it will be noted thatthis master blank holder 60 is ailixed to the carrier member 51 by theextended pins 10 and 1I. The extended pins 'l0 and 1I are looselymounted in the master blank carrier 60, the openings 12 and 13 beingvertically elongated slots. Master blank 62 is secured to the head 15 insome suitable manner as bil` means of an adhesive. The bottom surface 18of the head 15 is an accurately fiat surface. In order to provide anequally distributed pressure on the plurality of master blanks, a layerof resilient rubber 11 is provided between the master blank holder 69and the headl 15. A small clearance is provided between head 15 and theholder 60 so that a limited universal adjustment may occur to equallydistribute the pressure applied through the rubber 1T.

The sequence of steps in the operation of my apparatus is as follows:

Master blanks 62 and 63 which may be formed by depositing on a glassplate a crystalline layer of, for example, I. C. S.-a, as is describedin my Patents Nos. 2,104,949'and 2,199,227, are afdxed to the headssimilar to 15 by means of suitable cement. 'A sheet of cellulose acetate52 carrying blank holders 60 and 6|| moving said master blank holders 90and 6| downwardly against the action of the relatively weak springs and59 and finally pressing crystalline layers. and 55 against thethennoadhesivecoated cellulose acetate sheeting 52.

When pressure contact is established, a suitabledegree of pressureiseXerted for a proper predetermined period of time as set on a timingdevice which is a part oi' the electrical circuit to be described toeilect the. pressing of the layer of crystalline material 4on the masterblank onto the receptive thermoadhesive coated cellulose acetate medium.

Prior to and during the application of the pressure the temperature ofplaten 30 is raised l by passing a heated fluid 'such as steam or hotsive coating on the cellulose acetate sheet 52. As

a suitable receptive adhesive coating is dropped the piston rod 20descends, full pressure being reached upon contact of the master blanksand the cellulose acetate sheet on the backing surface plates 50 and 5|,the pressure is equally distributed among the master blank holders shownin Figure 2. By reason of the resilient member 11 between the blankholder 66 and the master blank head 15, an equal pressure on all masterblank holders is assured as well as an equally distributed pressure overthe entire area of the crystalline layer 54 and the plastic receptivemedium into which it is pressing.

The mechanism is then released by the practically simultaneous releaseof the vacuum and the release of the pressure upon the piston rod 25causing the springs l5 and I9 .to move the crossbar vI1 upwardly lthusraising the vacuum hood 22 and the pressure head 2|. Upon being soreleased the springs 5l and 59 raise the master blank carrier plate 51upwardly carrying with it the master blank holders 60 and 5|.

The master blanks which are in adhesive conv my invention, t .H

assauts then removed together with the vmaster blank holders attachedthereto. The cellulose acetate sheeting is then stripped from the masterblank, this stripping eilecting the cleavage of the crystalline layeron'the master blank faces so that crystalline ,fieldset-layers remainattached'to the cellulose acetate sheet, and to the master blank.

Then by a suitable method and apparatus which is more specincallydescribed in my copending application Serial No. 331,937 and my PatentNo. 2,199,227, I intensify the master blanks B2 and t3. and thecrystalline neld which is aiiixed to thecellulose acetate sheeting t2,to complete the otion cycle.

I have provided' for automatically eectuating the above c ence ofoperations by means of switcliw locatedon the apparatus oi switchesbeing actuated by predetermined movements of the apparatus. theseswitches cooperating with electric timerlmechanisms and relay circuitsinteracting with amotor for the oil p p and a motor to the vacuum pumpthe vacuum and'oil pressure system, theaction of which is timed inaccordance with a predetermined cycle. Y

The cycle oi operations is initiated by an operator pushing a momentarypush button through contact IM which energizes the relay coil |62.

also the' solenoid valves in |12 which'sta'rts the motor |1I, thestarter |12 being o! a conventional type.

Referring now to Figure 4 solenoid |30 has been closed by theenergization of circuit as shown' in Figure '1,- thus closing thesolenoid oil valve |32. Motor I1| driving pump |10 forces oil fromreservoir |19 into the main cylinder 200 and into accumulator cylinder26|. Raising the pressure of the oil in 200 causes the downward travelof piston 20 against the springs I8 and I9 which carries downward thecrossbar l1 and vacuum j hood 22 which contacts the gasket 29 andsimultaneously by means of extension 42 closes switch Closing switch `|2energizes relay coil I2| which thereby makes contacts |22V and |23 andbre contact |24. The breaking of |24 deenergiz relay |15 thus stoppingmotor |1| and stopping oil pump |10. Check valve 202 prevents the oil incylinders 200 yand 20| from backing up into the reservoir/|19.Consequently pressure head 3i stops in its downward travel and re-Energizing the relay coil |92 closes the contacts |03 and IM whichcontacts remain' closed, contact iliacting to maintain or hold thecircuit until the current therethrough is interrupted. (See Figures 4and 7) Relay coil |02 is in .series with a parallel ciricuit consistingoi a single set of contacts |09 actuated by relay coil it?. and singleset ci' contacts ills. actuated by a relay coil iid, |09 and |08 beingnormally open.

Tho'switoh 9i which-is positioned at the point of farthest downwardtravel of the cross bar l1 is normally closed and in this 'closedPosition it energizes the coil il@ which in turn closes the relay switchHit.

The relay switches itt and |04 are normali onenfand when closed theswitch |06 holds the circuit while the switchV |63 simultaneouslyactuates thesolenoid oil valve |80 and the relay coil iti which are inparallel. Hence the closing of the switch mi theA contacts |33, andiboth y the atmosphere ISI.

mains .motionless at this stage oi the operation.

Simultaneously the closing oi contact |23 energiz'es relay coil |53through contact |33 which has previously been clod by the relay` coil|3|,

relay coil ii having been energized at the out;

set ofthe cycle by the holding coil circuit of Figure '1. Energizingcoil |55 simultaneously closes to the desired preset pressure. The timeperiod can he set on timer li. Alternatively, I and |5i could bereplaced by a vacuum pressurestat which would operate switch contactsdirectly.

Simultaneously the energizing of coil |2| closes contact |22. Referringto Figure 6, the closing of the relay it! and also simultaneously closesthe solenoid oil valve ist. It is to be understood that the circuitshown in Figure 'I is closed dui-inf;4

the operation of the cycle steps labove set 'forth `and the closedcircuit is maintained because the relay |08 is closed before the relay|09 is opened.

This reroutins will be explained Ilater at the time of its occe.

Referring now to Figure 5.4 contact |33 on' relay itl has heen closed aspreviously explained. y

Contact lei as yet is open since the timers IBI normally open,closes-after a of contact i completes the circuit, thus actuating timermotors ISI and |53 by a time-Inonitfired Timers Ibi and |53 areconventionally known as reset timers or time delay switches. 'Timer lloperates as follows:

Upon ii being energized,

dial of timer Isl. switch Isn remains' closed until the current throughtimer il is interrupted whereupon the timer automatically resets and isprepared to repeat this operation upon re-e n ergizing;

Timer |58 operates similarly except that its contacts it are normallyclosed. and open after a time that is preset on d ial of timery |53, the

and |53 have not yet-been actuated. However.l

contact |26 on'relay. 62| is normally closed and consequently thecircuit through relay |15 is coni pleted inasmuch as the accumulatorswitch |18 is also closed.' The accumulatonswitch |10'is normally closedand opens only when pressure in the accumulator rises to some 'presetvalue.

Thus |16 in conjunction with accumulator armI |11 acts like a pressure'stat. c

Returning -nowto'relafv coil'l, contact |18 is closed by the energizingof relay coil |15. The

closing of m actuateo the remote control starter' '(5' closins'ofswitehl tous timer resettingupon motor |58.' A

Since switches |80 and |52 are in series, l! time ti is set on dial |5|and'time t: is set on dial |88A the series circuit will be open fortime.

-de-energizing of the timer t, t1, then closed for time ta-ti andthereafter opened, this sequence repeating upon thede-V energizing andthen re-energizing of the timer' motors ll and l|53 which are lnparallel. y

Returning toV the sequence .of operations occurring in the apparatusshown in VFigure 1, the' the pressure head 2|l son@ so vwhich-1s' timepreset -on the faces without the interference of atmospheric A pressurewhich would be manifested by bubble formation and consequent loss ofcontact at the bubbles.

Upon the closing of switch |20 the timers |5| opens thereby`cle-energizing relay coil |00 and and |53 are started by theclosing ofthe circuit through |22 and |34 which have been closed asabove-described.

When the time t1 which has been set on |5| has expired, the time beingmeasured from closing of through the interval necessary to establish theproper vacuum,` contact switch |50 is closed thereby establishingcircuit through |52v which is normally closed and consequentlyenergizing relay coil |40, simultaneously closing contacts |4| and |43.

Referring back to the motor control circuit of Figure 5, it is notedthat contact |33 is still closed, contact |24 having been opened byclosing of switch |20. vNow, however, the timers have closed |4| therebytemporarily actuating the oil pump |10. The effect is to continue thedownward motion of pressure head 2| whichengages the master blankholders 50 and 6| and presses the crystal layers 04 and 65 into pressurecontact with the plastic medium 52.

There is provided in the oil system a-pressure relief valve 206 whichprevents the pressure in the system from exceeding a predeterminedmaximum pressure necessary for the pressing operation. I have alsoprovided an accumulator 20| which stores up pressure to maintain aconstant pressure in the cylinder 200. The accumulator 20| also acts asa pressure-stat by causing the piston to open and close switch |16 asthe pressure within the system becomes too high or too lowrespectively.It can be seen from Figure 5 that |18 alone controls operation of oilDump |10, other elements in this circuit being closed. The pressurefor-downward movement before pressure contact being low and rising verysuddenly as contact between master blanks and receptive plastic mediumis established, the functions of the accumulator are important in thatit causes the pressure in the system to increase at aucontrolled rate.The accumulator therefore acts as a pressure cushion and reservoir.. Italso accommodates for any leakage in the system.

Simultaneously with pressure contact of the master blank and thecellulose acetate, the downward movement of piston 20 causes the openingof switch 92 which de-energizes relay coil ||0 thus, opening switch |09.Referring now to Figure 7, the circuitthrough |50 and |52 has energizedcoil |40 closing contact |43, thereby energizing relay coil |01 andclosing contact |06. Consequently the current through holding coil |02has been rerouted through switch |06 before contact |09 is Aopened byactuation of switch 92. The crystalline layers -34 and 55 are now beingpressed into plastic layer 52 for a time tz-ti and the heat from chamber45 softens the ther- `moadhesive coating on the upper surface of thecellulose acetate sheet 52 therefore rmly bonding the outer portion ofthe crystalline layer 54 and 65.

At the end of the predetermined time intersimultaneously openingcontacts |4I, and |43. The opening of contact |43 de-'energizes relay|01 breaking switch |03 thereby de-energizing the holding coil |02causing contact |03 to open. I'he opening Aof |03 de-energizeselectromagnet |30 and also de-energiz'es coil |3| thereby breakingcontacts |33 and |35. The opening of oil valve |32 caused by thede-energizing of |30 enables the oil in the cylinders 200 and 20| toempty into |19, the pistons 20 and 201 moving upwardly under pressurefrom springs I8 and I9 and 208 and 209 respectively.

val ta-ti during which this -impressing operaf tion is taking place, theswitch |52 of timer |53 The opening of |35 de-energizes relay coil |55,thereby stopping vacuum pump |82 and opening air valve |9| to theatmosphere, thereby enabling the pressure Within operating chamber 4| toreturn to atmospheric pressure.

The piston 20 moving upwardly under impulse springs I0 and |9 carriesvacuum hood 22 up thereby opening switch |20 consequently openingcontacts |22 and |23 and closing contact IM.

As shown in Figure 6 contact |22 upon opening de-energizes timers |5|and |53 which reset for the next cycle.

To prevent the excessive emptying of cylinder 200 and 20| when valve |32is opened, a low pressure-relief valve 2| 0 is provided in the systembetween the oil valve |32 and the reservoir |19. 'I'he function of therelief valve 2|0 is to prevent oil under pressure lessthan a given limitto pass through the valve from the cylinders to the reservoir |19. Thusthe cylinders are not completely emptied upon the opening of the valve|32, they are merely emptied to a sufficient vextent to permit thereturn of the piston to a starting position. Thus whenq starting thecycle anew, no undue period is required for building up pressure in thecylinders.

From the cycle of operations and the controls therefor which have beendescribed above, it can be seen that, after the coated cellulose acetatehas been placed over the backing surface plates 50 and 5| and thecarrier plate 51 carrying the master blanks is placed upon thesupporting springs 58 and 59, the operator initiates the cycle ofoperations by means of a push button |0| causing the proper sequence ofconditions and operations to be carried out automatically. Upon the endof the cycle the master blanks with the cellulose acetate sheet 52attached thereto can be removed from the apparatus for separation.

It is particularly important that the backing surface plates 50 and 5|and the face of the head 15 be accurately flat in order to insure acomplete and equally distributed pressure on the crystal layers andplastic medium. By means of 'the loose mounting of the master blanks 62in the carrier members 60 within the carrier plate 51, I compensate forany unequal pressures that might be set up. This 'is important becauseit is a primary object of this apparatus to insure an -even fiat contactbetween the crystalline layers and the plastic medium in order to obtaina complete contact therebetween for effective transfer.

By resiliently or yieldably supporting the carrier plate- 51 with the.master blank holders loosely mounted therein above the backing surfaceplate 50; ,the vacuum which is set up in the operating chamber 4| can beeffectively utilized. The vacuum outlet 53 serves not only as a meansfor evacuating the chamber 4| but also as a means foraccuratelypositioning the plastic medium 52 which may be in the form of a coatedsheet of blank. Too rapid a drying also accentuates the irregularitiesof the crystal surface.

Accordingly. I prefer to employ a coating lacblank should be intensifiedunder controlled conditions before rtransfer is effected of the crystallayer of the master blank on to a support.

I have found that in order to transfer heat from the heated backingplate tothe adhesive coating on the cellulose acetate lm that it may bedesirable to employ on the back of the acetate hn or on the metalbacking surface, a illm of liquid adapted to transfer heat, such as "alm of oil. When a thin film of oil is applied on to the back of thecellulose acetate illm, it vfacilitates the conduction of heat from theheated backing member to the thermo-adhesive coating on the celluloseacetate film and thus the coating is properly softened to receive thecrystalline illm to be transferred thereto. I'his is 'of particularimportance since the-pressing operation is carried out in vacuum andeven a thin vacuum Spacing between the fiat plate and the plastic filminhibits the transfer of heat except by radiation.

With the use oi an oil illm, a thinner and more uniform thermoadhesivecoating may be employed. Thus in lieu of the '120 c. c. butyl acetate`solvent oi' the Formula A, I may use as high as 2500 c. c. of butylacetate and a lower backing `ur1igBceFtemperatura e. g. on the order of180 It is necessary to create such a temperatureand pressure conditionthat the thermo-adhesive coating will ilow and become receptive to thecrystalline field .but the plastic support such as cellulose acetatewill not flow'. In other words. the thermo-adhesive coating becomesmoldable and is molded by the impression oi' the crystalline fieldthereon.

' ton rod. a pressure transmitting head'mounted It is within thepurview-of my invention to v eliminate the use oi' this thermo-adhesivecoating and employ a plastic support under such conditions oftemperature and pressure that the plastic support can receive andretainthe crystalline on said piston rod, a vacuum hood mounted on said pistonrod and disposed over said pressure transmitting head, a platen andmeans for resiiiently pressing said vacuum hood against said platen.

3. An impresser mechanism comprising a frame, two tension rods mountedon said frame, a crossbar on said two tensionI rods, springs disposedover said tension rods and supporting said crossbar, a piston rod, saidpiston rod engaging said crossbar, a pressure transmitting head mountedon said piston rod, a vacuum hood slidably mounted on said piston rod inairtight contact therewith.

4. An apparatus comprising a base, a hood, means for moving said hoodinto sealing engagement with said base to form a vacuum chamber, meansfor evacuating said'vacuum chamber, said means for. evacuating saidvacuum chamber being actuated immediately after said hood moves intosealing contact with said base, a pressure element adapted to perform, apressing operation located within said hood, means for causing saidpressure element to be actuated after a predetermined condition ofvacuum is established within said vacuum chamber, said means for causingthe pressure element to be actuated including a time control element,means for breaking the vacuum in the vacuum chamber after the pressureelement has performed its operation, and means for retracting saidpressure element and said hood from said base.

5. An apparatus comprising a base, a hood, means for moving said hoodinto sealing engagement with said base to form a vacuum chamber, meansfor evacuating lsaid vacuum chamber, said means for evacuating saidvacuum chamber being actuated by a contact control immediately aftersaid hood moves into sealing contact with said base, a pressure elementadapted to perform vent of the material that comprises the support.

.for the thermo-adhesive coating on the support.

' The index of refraction of the coating lacquer should bey as close aspossible to the index of refraction of the crystalline .iield andpreferably i should substantially approximate it, for maximum 4 opticalclarity.

g 'Ihe specinc phenomenon oi' crystal growth and ,'crystal transfer arefully set forth in my co- `pending applications Serial No. 313,392 andSea pressing operation located within said hood, means for causing saidpressure element to be actuated after a predtermined condition of vacuumis established within said vacuum chamber, said means for causing thepressure element to be actuated including a time control element,

means for breaking the vacuum in the vacuum chamber after the pressureelement has performed its operation, and means for retracting saidpressure' element and said hood from said base, said means forretracting comprising a spring mechanism.

' 6. An apparatus comprising a base, a hood, means for moving said hoodinto sealing engagement with said base to form a vacuum chamber, meansfor evacuating said vacuum chamber, said means. for evacuating saidvacuum chamber being actuated immediately after said hood moves intosealing contact withsaid base, a pressure element adapted to perform apressing operation located Within said hood, means for suspending workto be operated on between said pressure element and said base, means forcausing said pressure element to be actuated after. a predeterminedcondition of vacuum is established within said vacuum chamber so thatrsaid work is pressed by said pressure element against said base, saidmeans for causing the pressure element to be actuated including a timecontrol element, means for breaking the vacuum in the vacuum chamberafter the pressure element has perfumed its operation, and means forretract--I ing said pressure element and said hood from said base. f

7. An apparatus for the transfer oi a crystalline eld to a receptivemedium, comprising a base, a hood, means for moving said hood intosealing engagement with said base to form a vacuum chamber, means forevacuating said vacuum chamber, said means forevacuating said vacuumchamber being actuated immediately after said hood moves into sealingcontact with a pressing operation located withinv sind hood,

said base, a pressure element adapted to perform m a master blank holderholding a master blank having a crystalline iield on its face suspendedbetween the pressure element and the base, said master blank holderbeing positioned between said' pressure element and said base so as tobe pressed by said pressure element toward said 'base thus transferring,the crystalline field on the master blank to a receptive mediumpositioned on said base; means for causing said pres- 'sure element tobe actuated after a predetermined condition of vacuum is establishedwithinsaid vacuum chamber, said means for causing the lpressure elementto be actuated including a time control element, means for breaking'thelvacuum in the vacuum chamber after the pressure element has performedits operation, means for re'- tracting said pressure element and saidhood from said base.

ALVIN M. MARKS.

